Trimming mechanism



Oct. 7, 1941. a. T. KOCH TRIMMING MECHANISM Filed March 21, 1938 6 Sheets-Sheet l INVENTOR eai'ya TKac/Z BY I ATTORNEYS.

6 Sheets-Sheet 2 INVENTOR 'eorye 771 1. BY

v A TTORNE Y5 Oct. 7, 1941. e. T. KOCH TR'IMMING MECHANISM I Filed March 21, less Oct. 7, 1941. KOCH 2,257,965

TRIMMING MECHANISM Filed March 21, 1958 6 Sheets-Sheet 3 INVENTOR N 'earye Tlfoal.

TTORNE Y5.

Oct. 7, 1941. G. 'r. KOCH TRIMMING MECHANISM Filed March 21, 1958 6 Sheets-Sheet 4 INVENTOR ORA/5K BY W G'earye 7YKO1 Oct. 7, 1941. G KOCH TRIMMING MECHANISM 6 Sheets-S heet 6 Filed March 21., 1938 INVENTOR Gav ye 7%( 1.

BY W, A TTORNE K5.

.obstacles to the design and construction of a Patented Oct. 7, 1941 v UNITED STATES, rnrsisr OFFIC TRIMMING MECHANISM George T. Koch, Detroit, Mich., assignor to The Murray Corporation of America, Detroit, Mich., a corporation of Delaware Application March 21, 1938, Serial Nb. 197,206.

1 Claim; (91. 164-29) i The present invention relates to mechanism for trimming the margins of sheet metal stampings. It is relatively common practice, particularly in the manufacture of automobile bodies, fenders,

etc., to form by sheet metal drawing operations 7; large complex stampings. .the drawing operation it is necessary to clamp In order to perform the edges of the sheet of metal with the result that the clamping dies of the drawing press form flanges on the stamping which, with any excess material that may be present, must be trimmed off the stamping. in a. subsequent operation. Stampings are frequently formed with marginal portions at or near a right angle with respect to themain or center body of the stamping, and in 1 such cases trimming cutters which operate on these marginal portions must operate in a plane substantially parallel to the'main body of the stamping. This requirement presents serious performing trimming operations in two planes at right angles to each other; but this form of mechanism has a number of serious disadvantages among which is the fact that the horizontal operating cutters are positioned outside the confines of the stamping thus necessitating the use of .a press of larger size than would be required to ac commodate the stamping itself. In addition, in the .Groehm mechanism the outer horizontally movable cutters are so arranged that they block access to the trimmed scrap and interfere with its removal from the mechanism.

It is one object of the present invention to provide a trimming die or mechanism of the type mentioned which is exceedingly compact, and which therefore can be used on smaller presses than can prior devices of the same class. I

Another object of the invention is to provide a trimming mechanism of the type mentioned in which the strips of scrap metal trimmed by the mechanism are accessible to the operator for ready removal from the mechanism.

Another object of the inventionis to provide I a mechanism of the type mentioned adapted to trim entirely around the periphery of a sheet metal stamping in a single operation.

. Other objectsof the invention which include the provision'of an improved arrangement of ,it leavesthe drawing die.

cutters, and an improved and simplified arrangement of parts, will become apparent from the following specification and the accompanying drawings. v

In the drawings,

. 1 Figure 1 is a side elevation of the trimming mechanism showing portions upon the press upon which itis, installed.

Fig. 2 is a fragmentary plan view taken on the .line .2 2 of Fig. 1, showing one of the upper cutters at the forward corners of the machine.

:Fig; 3is an end elevation of the pair of cutters ,atonefront corner of the machine.

- Fig. 4 is a plan view of the mechanism having parts broken away to show the interiorconstruc- ,tionf.

Fig. 5 is alongitudinal section view taken. on the line ,5-. 5.of Fig. 4.

Fig.6 is afragmentary section View taken on the line 66 of Fig. 4.

Fig. .7 is a section view taken on the line 'I! of Fig.4. with the parts in partly open condition.

. Fig. ,8 is a section taken on the line,1-1 of Fig. 4 -with the parts in closed position.

Fig. 9,is a section taken on the line 9,9 of Fig. 4.

Fig. 10 is a section taken on the line I0I0 of Fig. 11 is a perspective view of the sheet metal stamping which the trim mechanism shown in Figs. 1.-10 is designed to operate upon.

,Fig- 12 shows the sheet metal stamping after ,it has been trimmed. ,1 Fig. 13 is a fragmentary sectional view taken .l'on the line. l3-I3 of Fig. 11.

In Fig. 11,, ofthe drawings there is shown an automobile body, panel A in the condition in Which The panel A, shown for the. purpose of illustration, is' a one-piece top and rear .quarter panel for a coup, but it will be understood that the present invention is applicable to' similar panels for other automobile .body stampings,.and that if desired the panel may also be extended at the front to include the front' pillar elements or at the rear to include the complete rear back of the automobile body, or both.v .The invention is also applicable to other sheet metal stampings such as automobile fenders and the like.

The drawing die, not shown, is provided with elements for gripping the periphery of the panel prior to the drawing operation, and these gripping elements form a flange B having grooves C in a substantially horizontal plane.

of the type here involved it is highly desirable, if not essential, to perform some of the trimming operations by shearing in a horizontal plane, and others by shearing in a vertical plane depending upon whether or not the panel at the point under construction extends nearer to the vertical or nearer to the horizontal. Where the margin of the panel at any given point extends in a generally vertical plane horizontal shearing is necessary to avoid sub-sequent finishing opera tions or increased die cost. For example, in Fig. 13 there is shown a section of the panel A taken on the line |3-l3 of Fig. 12 in which the desired trim line is indicated by the dotted line X. At this point on the panel, if it were necessary to shear. in .a .vertical direction it would be necessarytoprovide on the .panel aclamping flange D vshownindotted lines, and thenshear vertically on th line Thereafter the remaining horizontal projecting flange portion would have to .berolled until its edge fell ontheline X. This .rollingoperation is expensive .and troublesome.

Moreover, difliculties may beencounteredin pro- .vidinga clamping flange atthe point D due to the well known requirement that the plan-e oi theperipheral gripping surfaces on thedrawing .die must be of suchconfiguration that a flat sheet of flexible materialwill .conformthereto .without wrinkling or stretching. Thisrequirement frequently prevents the formation of a clamping flange at or near the desired trim line. If the holding flange cannot be locatedat the proper point with respect to the .trim line, then, if vertical shearing .is. to beusedit is necessary to so shape the drawing die that it willform a special horizontaltrim flange in a different plane from .the holding flange; obviously an expensive expedient. .Thesituation is justthe reverse where, as at therear-of thepaneLA, thepanel extends There vertical shearing must be resorted to.

In the particularmachineby which thepresent invention is exemplified suitable shearing cutters .are provided fortrimmingtheentire periphery .of the panel A along the trimline X ina single operatiomand-atthe same timecut the peripheralsevered portion at the fourtcorners on lines Y. The shearing cutters which operate on thetrim line fall into groups, .someoperating in-a'horizontal plane and others operating in a vertical plane. 7 At each side of th panel along those-portions of the trim line indicatedE-in Fig. 11, the shearing cutters operateona horizontal plane. The same .is true of the shearing cutters which operate .along that portion of the trim line at he front of the panel .which is indicated G in .Fig. 11. All of the .remaining shearing cutters, namely those which .operate along the rear of the panel at H and the front corners at K, operate in a vertical plane. .It will be understood that the particular arrangement of vertical and horizontal shearing areas is controlled by the shape of the panel and the contour of thetrim line, and will be different for panelsof different shapes and contours.

In Figs} to of the drawings there is, shown the details of a machine adapted to perform the l trimming operations above described. The trimming mechanism itself is mounted in a con- .ventionedpower press having a movable upper press head I, and a stationary bed 2 indicated iragmentarily in Figs. 1 and 5. Secured in any desired manner to the movable press head I .is an upper die member indicated generally .at -3. Alower die member indicated generally at .4 is

mounted for vertical sliding movement with respect to the bed 2 on guide pillars 6 shown best in Figs. 1, 4 and 'I, which are fixedly mounted in a base plate 8 that is secured in any desired manner on bed 2. A plurality of springs I0 are positioned between the base plate 8 and the lower die 4, and exert a constant upward force tending to maintain the die 4 in elevated position withrespect to the base plate. The lower die 4 is also constantly urged upwardly by a plurality of pins H which project through suitable openings in the bed plate 2 and base plate 8, and engage the under side of the lower die 4. Pins ll are forced upward by a head l2 on a pneumatic cylinder l3 which is connected to a .-.sur.ge .tank .in the usual manner, .not shown. Thepins i ,l vand the pneumatic cylinder operate .asapneumatic spring which. aids spring 10,.and together-they.lnormally support the .lower die .4 sin the;elevated..position shown in Fig. '7. Suitablecapscrewsand associated sleeves l4 limit upwardmovement.orlthe lower die to the position .there shown.

..The .upperidie. .3 aisprovided with four down- .WardprojectionslB, oneateach corner, andthe projections 15 have suitable guiding bores for .receivingtheupper ends of pillars 6, with the result that...tl1e .upper ..die is guided with respect ..to:.the,1lower. die by means ofthe pillars 6. The bottom. surfaces .ofthe projections 1.5 are provided...wi th .wear .pads J5 adapted to engage similar wearpads .1] carried by the lower dieA, asbest shownin Figsgland 8.to.limit downward .movementof the .upperdie withrespect to the lower -die, .for .a purpose, hereinafter set forth. The 1OWI.dii4 atitsends as best shoWn'in Figs. .1, 4 .and.5, is provided .with upward projections 19 .extendingabovethe lower positionv of the pro.-

jections.JBJontheupperdie, and wear plates 20 .and12l are provided upon the projection l9 and .engage the sides of projections I15 to .assist pil- 13,115 .6 .in guiding the the members 3 and .4 .for .movementrelative to each other.

When the upper die 3 moves downwardlydur- .ingthe trimming operation, in themanner hereinafter described .in detail, .the abutment .Wear plates :16 and J! .on projections 15 and lower die :4, respectively .engage, and the lower die 4 is .iorceddownwardlyby the upper die against the .actionof springs 1.9 and .pins II. The lower diejsguided -during its vertical movement relaztiveto the base plate :8 by pillars 6 previously described, .and .also by .wear plates 22 and 24 -mounted on .projections 26 .on the ends of the :haseiplate:8,.as best shown in Figs. 5 and 8. 'It will :be lnoted that the projections .26 and the .wear plates 22 and .24 mounted thereon project upwardly into suitable slots in the ends of the lower die 4.

The upper die 73 .is provided adjacent its mar- ;gins with downwardly extending end webs '39 and side .webs:3;2 defining a continuous flange havin 'it inner edg o bstantially the sam nfi a i n a th hor zontal;p oie 0n.0f he trim line}! on panel A. The webs 32 at the sides of the die connect projections l5, while webs :30 extend between webs 32 somewhat inwardly of the projections l5. Fixedly secured to the loweredges of webs :30 and 3.2 are a plurality of shearing cutters arranged in groups. At .each-side of the-machinea pluralityof shearing cutters. 34 are-secured .by cap .screws35 .in suitable recesses in.a .tool holding block .36, which in turn is'secured in .any suitable .manner to the bottom edge {of ,the. .web 32 ,at that side of the cutters 34 maybe formed of'uniform thickness, and have their lower or cutting edge'con- "form to; the horizontal projectionrof thetrim line at thes'ide of the panel. The two groups of cutters 34 have cutting edges at'the inner sideof the surfaces, and are adapted to cooperate with horizontally movable shearing cutters hereinafter described.

--Another series of cutters 38 at the front of the panelare secured by capscrews 39 to-a tool holding block-48, which in turn is secured to the adjacent end web 38 in any desired manner.

(See Figs 1; 5 and 9.) Cutters 38 are similar to cutters 34-previouslydescribed; and also co- -operate with horizontally movable shearing cutters hereinafter-described.-

At each front corner-of the upper die 3 at the intersection of webs'38 and 32 there is provided a cutter 42,'best shown in Figs. 1, 2 3, 4 and 9, comprising adownwardly extending flange 43 having a cuttingedge 44 adapted to cooperate upon vertical movement witha cutter mounted on the lower die to trim'the corner portion K of the trim line X.- Cutter '42 also has a downwardly extended flange 46 having an edge 41 adapted to shear the peripheral holding flange of the panel along one of the lines Y of Fig. 11 to cut the scrap into strips, thus facilitating its removal from the mechanism;

At the rear web 38, and along the rear portions of the side webs 32-there is provided a continuous line of cutters 58, the lower edges of which are-adapted upon "vertical movement to "cooperate with cutters mounted on the lower die 4 to shear the panel vertically along the portion H- ofthe trim line X in Fig. 11. The cutters 58 at the rear corners are similar to cutters42 previously described, being provided with diagonally extending cutting flanges 52 for splitting the peripheral flange Eat the panel along the lines-Y in Fig. 11. Cutters 58 are secured by cap'screws to a U-shaped tool holding block 5| carried in any suitable manner on the rear web 38 and the rear ends of webs 32.

The cutters 34,- 38, 42 and 58,'al1 of which are fixedly secured to the upper die, have contiguous cutting edges forming in effect a continuous cutting edge entirely around the trim line X. In addition the upper die is provided with cutting blades 46 and 52 extending diagonally outwardly along the lines Y in Fig. 12 for severing the scrap into strips.

As best shown in Figs. 5 to inclusive, the upper die 3 is provided with a presser member 68 positioned within the webs 38 and 32, and providedlwith a downwardly extending peripheral flange BI having its bottom edge shaped to engage and fit panel A inwardly of the trim line. The outer surface of the flange 6I has a guiding engagement with blocks 36, 48 and 5|, andis flush with the inner faces of cutters 42 and 58. The presser member 66 is vertically slidable with respect to the upper die 3 on studs 64, having sleeves 65 mounted thereon. The sleeves 65 are suitably flanged to limitdownward movement of the presser member with respect to the upper die at the point shown in Fig. 7. A plurality of coil springs 66 between the upper die and the presser member 68 normally constantly urge the presser member downwardly with respect to the die. These are four springs 66, and four studs and sleeves 64 and 65, one at each corner of the presser member, as best indicated in Figs. 4 and 5. v. 1

- The lower die llis termed as a heavy casting having an---inner [vertical wall'18 providing a central opening which is generally T-shaped in plan; The headof the Textends from side to side atlthe forward endj'of the die'in the plane of; the left hand side of the section shown in Fig. 9. The wall "I8 -isprovided at'its top and bottom edges with outwardly extending parallel flanges I2 and 14 which form the top and botat the stem of the-T, as best shown in Figs. 4,

5 and 18. 7

A work supporting member 86 is mounted-on the die 4 by means of three centrally positioned legs 88,89 and-.98. Legs 88 and 89 seat upon cross members 88 and 82 respectively, and leg 98 seats on the flange 12 at the rear of the die, as best shown inFig. 5. Longitudinally aligned keys 9|, 92- and -93 shownin Fig. 5 are secured to the lower die by means of slots and cap screwsand fit in aligned slots on the legs 88, 89 and -98 respectively, to properly locate the work support 86 transversely'with respect to the lower die 4. A" pair of aligned transverse keys 92 are similarlysecured to cross member 88, and engage in a slot in the leg 88 of the work support 86 for positioning the work support longitudinally on die 4, as best shown in Figs. 4, 5 and 10'. The periphery of the work supportis'shaped to conform to the panel A throughout the areas E and G of Fig. 12,as best shown in Figs. 5, '7, 8, 9 and 10, and in these areas engages the panel on theunder sideofthe area engaged by plate 6| or the presser member. At the'rear of the machine the work support 86 terminates on a line intersecting the junctions of areas E with area H, as best shown-in Fig. 5. A plurality of stud bolts 94, one'of which is shown in Fig. 5, are provided for securing thework support 86 on the lower die. A tool supporting block 96, shown in Figs. 4, 5 and 6, is secured by cap screws to the rear flange I2 of the lower die and carries a plurality ofshearingcutters 98 adapted to cooperate with the cutters 58 to shear the panel A vertically along that portion of the trim line indicated G in Fig. 11. A pairof scrap cutters I 88 are secured to flange 12, and cooperate with cutters 52 to sever the trimmed material along the rear lines YpfFigll. Q

' At the forward corners of the lower die are secured a pair of cutters indicated generally at I82 each having a cutting member I84 adapted to cooperate with the inner side of flange 43 of the associate cutter member 42 on the upper die 3 to trim the panel A at on of the corner areas K. Cutters I82 are also each provided with a diagonally extending cutter I86 adaptedto cooperate with thescrap cutter 46 on the upper die to'sever the trim material along the lines Y at the front of the panel.

, All of the cutters 98, I88, I84 and I86 are fixedly secured to the lower die, and they are adapted to cooperate with the cutters 58, 52, 43 and 46 respectively, when the die members 3 and 4; approach each other to vertically shearrthe panel A along the trim line at the areas K and H of Fig. 11, and also to sever the trimmed material at the lines Y into tour easily removable scrap 'stripsi 'Coil'springs I8 and the pneumatically spring urged pins -l-I prevent any substantial downward movement cf the lower die luntil after the vertical shearing of areas K and --H-is completed. The parts are so arranged that immediately upon completion ofthis .verticalshearing operation wear pads-:46 and IT on the dies ,3 and 4, respectively, contact each other, and thereafter any further downward movement of the upper die causes a similar downward movement of the lower die 4 :against springs I and pins II. This downwa-rdmovementof the lower die operates-means hereinafter described to effect horizontal shearing operations.

At each sidep of themachineandlfesting on lower die 4 is a tool holding block III] which extends the full length of the horizontal shearing area E of the trim line, as ,best shownin Fig. 4. The blocks H0 rest upon a plurality of bronze wear pads I I-2 which seat in suitable recesses-inflange 12 of-die '4 .andtheunder side of-eaoh block H0 is provided withgrooves adapted to receive the key member 92,gas shown in Fig. 10. Each block IgIU is providedon its top surface with'recesses -I I A, I I'5 and-IrI6 in which are received bronze wear pads ;I I1, "H8 and H9 respectively, which are secured to the underside of thework support 85. The bronze-wear-pads and'key 92 guide the blocks IlI'lfortranslatory slidingmovement on lower die 4. Blocks 1 III-are normally urged; inwardly; by means of a plurality of coil springs .IZZ, whichzengage between the outer sides of each block H0 and a block I 24 which is secured to the edge of flange -12 by means ofcap screws T25. A-cover plate I26 encloses'the springs 122..

A plurality of shearing cutters -I2-8 arersecured to the outer sides of block band are adapted on outward movement of the blocks III), after wear-plates I6-and U have contacted to cooperatewith the cutters 34 onthe upper die, to shear .the panel horizontally along the sections E of the trim line. The innerside of each of theblocks -I lfl is provided with three-inclined cam faces I29, 136 and [SI adapted to cooperate with suitable cams hereinafter'described for forcing the blocks outwardly against the ,springs-IZZ to effect the shearing operation. A tool holding block I36 is sli-dably mounted on-flange 'li at theforwardend of the lower :die for translatory movement longitudinally of-thedie. A-key I38 shown in dotted lines in Fig; 9 fitsinsuitable grooves in the blocks :ISB and-flange lZ-to'maintainthe block in proper alignment. Bronze wear pads Mug-between the block I36 and flange 12-, and padsI42 between the block and the work support 86 guide and-support the sliding block I36. A pluralityof shearing cutters I43. are mounted on block 136 and cooperate with I cutters 38- on theupper die to shear the panel horizontally ,along section G of the trim line after pads I6 and I! contact and the block 1361s moved outwardly: Springs .444, similar to springs -I 2 -2.in construction: and arrangement normallyurge the blocks 1-35 inwardly,- while inclined I-cam faces I45 on block =l3'8 cooperate with cams hereinafter described formoving said block outwardly to effect the shearing operation. a V,

The means for--effecting outward movementof the blocks II 6 and block 136 carrying the horizontally movable cutters comprises a stationary casting indicated generally at I56 in Figs. 5, T7, 9 and 10. This casting is generally .I-sh aped .in transversecross section ,as ,bestshown in -.-Figs. 8 and 9, althoughatpneend, as shown in Fig. 9, the flanges are extended outwardly at vI 5 I. .so that .head IM is provided at each side with three inclinedbronzewearpads I66, ISI, and I62 in alignment with the transverse webs I56, I51 and I58 respectively, and adapted to-engage the inclined faces I29, I30 "and ,I3I on the adjacent block force the sameoutwardly when the lower die --m0ves downwardly with respect to the fbaseplatefi. At-the front end of the -machine the transversely extendedhead I54 of the I castingisalsoprov-ided at its forward side with a pair of inclined wear pads I66 adapted to engage the inclined surfaces I45 on block I36 to move the same outwardlyand effect the shearing operation .whenthe lower-die moves towards the base plate. The trim mechanism operates in the following manner. -At the'beginning of the trimming-operation the press heads I and.2 are separated t an evengreater extent than is indicated in Fig. 7, thus making it possible toplace an untrimmed panelA inthe-mechanism until it rests" upon the work support 86, andis properly located thereon. Atthis point in thecycle of operation the lower die .and remaining :parts of the mechanism are in thepositiOn-shOWn-in Fig.7. Thepress is then started, and as the upper die 3 moves down- .vvardly the vflange .6I on presser member -60-en gages thepanel and clamps it against the work support -86, and alsoagainst the topedge of the stationary vertical shearing cutters and IM inthe -manner. shown in Figs. 5 and 6. Upon furtherdownward-movement ofthe upper die 3, springs 6 which normallyurgezthe .presser member Bil downwardly willbecompressed due to the fact that they are insufficient in strength to overcome the force exertedby spring-s III and pins II on thelower die 4. Accordingly, the upper die 3 .will' continue to move 'downwiardly while the .presser member remains substantially stationary with the result that the panel will be sheared along the sections H and K by the vertical shearing knives .5098 and 43I-04 carried by the upper andlower die-members respectively. Simultaneously with theabove described shearing ac- 'tion,..the scrap cutters 45..I86 and 52I3D will severthe scrap strips alongthe-lines Y in Fig. 12. Upon completionof this shearing operation wear pads I6 andlII on the upper and lower dies respectively engage each other, thus limiting further downward movement of the upper die relative' to the lowerdi'e at the point shown in Figs. jl, '5,,6, 8, 9 {and .10, inwhich position the cutting edges. on the horizontal movable cutters 34 and I 2,8.yi hich cooperate to shear the area E on the panel and cutters .38 and IE3 which cooperateto shear the area G onthe panel are in the same plane and thereforeiin proper juxtaposition to perform the shearing operation. Thereafter as the upper .die ,3 continues to move downwardly anyfurther movement of the upper die towards ,the -lower. die 4 is impossible-so the two dies 3 and Arnove downwardly-as a unitagainst the aotionof springs J 0 andpins -I I. The downward movement of die 4 from the position shown in Fig. 7 to the position shown in Figs. 1, 5, 6, 8, 9 and 10 carries the two holding blocks III) and block I36 downwardly with respect to the stationary camplates I60, I6I, I62 and I66 on casting I50 with the result that the cam plates force blocks III] and I36 outwardly. The cutters I28 and I43 on blocks III] and I36 respectively cooperate with the stationary cutters 34 and 38 respectively during this downward movement to shear the plate along those sections of the trim line indicated E and G in Fig. 11, thus completing the trimming operation. The press is then reversed, and the upper die elevated to suflicient height to permit removal of the trimmed panel.

It will be noted that due to the fact that the stationary horizontal cutters 34 and 38 are carried by the upper die, while the movable horizontal cutters I28 and I43 are carried by the lower die and move outwardly to effect the shearing operation that the scrap strip is readily accessible for removal from the mechanism. In fact, it is possible to grasp the scrap strip prior to the shearing operation and hold onto it during the trimming operation until it is completely severed, and then remove it from the machine without any danger of injury. This is true of each of the four scrap strips that are formed during the trimming operation. It will be noted also that since the movable horizontal cutters are positioned beneath the work support 86, and move outwardly to effect the shearing operation that the mechanism is much more compact than is possible in a mechanism having inwardly moving horizontal shearing cutters, with the result that the mechanism can be operated by a much smaller press than the type of trimming mechanism having inwardly moving shearing cutters. This is a very important advantage in view of the fact that trimming mechanisms here involved must, as a practical matter, be installed upon conventional power presses which in general increase in power and weight in proportion to the size of the die area provided thereon. No great power is required to trim a stamping of the type under consideration, so the size of the press is controlled entirely by the size of the mechanism used, and it is highly desirable to use as small a power press as possible in order to avoid the expense.

It will be understood that the particular arrangement of cutters described above is governed to a large extent'by the shape and nature of the stamping for which the mechanism is designed, but that the principles and advantages of the invention are fully applicable to other detailed arrangements. For example, in some cases it may be advisable or necessary to eliminate one or more, or all of the vertical operating shearing cutters and replace them by horizontally moving cutters, and this may be done without departing from the spirit of the invention. If the vertical cutters 42 and I02 on the forward corners of the mechanism are eliminated they may be replaced by similarly horizontally moving cutters carried by extensions of blocks III) and I36. In such an event it will be necessary to overlap the blocks I I and I36 at their corners, but otherwise the arrangement would be substantially that shown.

While it is preferred to have the horizontally movable cutters carried by the lower die, as shown, it will be observed that so far as com pactness of the mechanism as a whole and accessibility of the scrap are concerned they could be carried by the upper die and cooperate with cutters on the lower die. In this event the panel A would be placed in the machine upside down. Such an arrangement would be the equivalent of turning the entire mechanism upside down.

Furthermore, while it is preferred to have the horizontally movable cutters move outwardly to perform the shearing operation, since such an arrangement results in a more compact mechanism, nevertheless it is possible to have the horizontal cutters move inwardly and still have the scrap strips accessible provided the horizontally movable cutter is carried by the upper die when the panel flanges are turned downwardly, or by the lower die if the panel flanges project upwardly. In other words, scrap accessibility is achieved by securing the outermost cutter, whether movable or stationary, to the die member opposite the die member toward which the panel flange projects. Or as stated in the claim, the outermost cutter must be located at the extreme projection of its supporting means in the direction in which the panel edge to be trimmed thereby projects.

It is apparent that various changes in the construction and arrangement of the parts shown and described may be resorted to without departing from the spirit of the invention or the scope of the appended claim.

What I claim is:

In a trimming mechanism, an upper die, a base plate, a lower die intermediate the upper die and base plate, said dies being adapted to receive a work piece therebetween, and to move toward each other, a pair of shearing cutters fixedly carried by the upper die, a shearing cutter fixed on the lower die and adapted upon movement of said dies toward each other to cooperate with one of said cutters on the upper die and thereby trim a portion of the work piece, a second shearing cutter slidably mounted on the lower die for movement in a direction substantially perpendicular to the direction of relative movement between said dies and adapted on outward movement to cooperate with the other of said cutters on the upper die when said dies are in a predetermined relative position to trim another portion of the work piece, a cam carried by the base plate and operable when said lower die is moved toward said base plate to force said movable cutter on the lower die outwardly, resilient means for maintaining said lower die in elevated position with respect to said base plate, means for moving said upper die toward said lower die and base plate, and means for limiting movement of said upper die toward said lower die upon completion of the operation of said shearing cutters on said first portion of the Work piece and at the point at which said dies are in said predetermined position whereby upon further movement of said upper die said upper and lower dies will move as a unit toward said base plate against the force of said resilient means and effect operation of said second shearing cutter by said cam.

GEORGE T. KOCH. 

